Narrative:

I (first officer) was flying the aircraft and captain was handling the radios on flight from bna to bwi. We were approximately 20 NM east of csn VOR on the ott 5 arrival at FL190 and were given descent clearance to 12000 ft by ATC which was read back by captain. My concern is because of the tone of voice from ZDC when she asked 'what altitude were we descending to?' we received a TA alert from a jet crossing from north of our position, but never was the TA closer than 5 NM. During the descent, passing approximately 13500 ft, ATC asked 'what altitude are you descending to?' which the captain replied '12000 ft.' very shortly thereafter (about 10 seconds) ATC gave us a 20 degree right turn followed by instructions to descend to 9000 ft -- all of which were read back by captain. After approximately 3 mins, we were told by ATC to descend to 6000 ft and proceed direct deale intersection. We completed a visual approach procedure to runway 33L at bwi. Supplemental information from acn 493197: vectored off STAR in vicinity of csn VOR. Later given clearance direct to ott. Given a descent to 12000 ft, which was set in altitude alert window. We received a TA on an aircraft north of us by 5-6 mi which was climbing out. ARTCC gave this aircraft a turn and at this time I noticed the aircraft climbing out of the undercast which had tops at about 11000 ft MSL. We were given a turn and nothing more was said about it. My first officer, our new hire jump seat rider, and I all agreed that we had indeed been cleared to 12000 ft.

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Original NASA ASRS Text

Title: A DSNDING B737-300 FLC QUESTIONS THE TECHNIQUE AND CLRNC AS EVINCED BY THE ZDC CTLR DURING A POTENTIAL CONFLICT WITH DEPARTING, CLBING TFC 20 MI E OF CSN, VA.

Narrative: I (FO) WAS FLYING THE ACFT AND CAPT WAS HANDLING THE RADIOS ON FLT FROM BNA TO BWI. WE WERE APPROX 20 NM E OF CSN VOR ON THE OTT 5 ARR AT FL190 AND WERE GIVEN DSCNT CLRNC TO 12000 FT BY ATC WHICH WAS READ BACK BY CAPT. MY CONCERN IS BECAUSE OF THE TONE OF VOICE FROM ZDC WHEN SHE ASKED 'WHAT ALT WERE WE DSNDING TO?' WE RECEIVED A TA ALERT FROM A JET XING FROM N OF OUR POS, BUT NEVER WAS THE TA CLOSER THAN 5 NM. DURING THE DSCNT, PASSING APPROX 13500 FT, ATC ASKED 'WHAT ALT ARE YOU DSNDING TO?' WHICH THE CAPT REPLIED '12000 FT.' VERY SHORTLY THEREAFTER (ABOUT 10 SECONDS) ATC GAVE US A 20 DEG R TURN FOLLOWED BY INSTRUCTIONS TO DSND TO 9000 FT -- ALL OF WHICH WERE READ BACK BY CAPT. AFTER APPROX 3 MINS, WE WERE TOLD BY ATC TO DSND TO 6000 FT AND PROCEED DIRECT DEALE INTXN. WE COMPLETED A VISUAL APCH PROC TO RWY 33L AT BWI. SUPPLEMENTAL INFO FROM ACN 493197: VECTORED OFF STAR IN VICINITY OF CSN VOR. LATER GIVEN CLRNC DIRECT TO OTT. GIVEN A DSCNT TO 12000 FT, WHICH WAS SET IN ALT ALERT WINDOW. WE RECEIVED A TA ON AN ACFT N OF US BY 5-6 MI WHICH WAS CLBING OUT. ARTCC GAVE THIS ACFT A TURN AND AT THIS TIME I NOTICED THE ACFT CLBING OUT OF THE UNDERCAST WHICH HAD TOPS AT ABOUT 11000 FT MSL. WE WERE GIVEN A TURN AND NOTHING MORE WAS SAID ABOUT IT. MY FO, OUR NEW HIRE JUMP SEAT RIDER, AND I ALL AGREED THAT WE HAD INDEED BEEN CLRED TO 12000 FT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.